add warning/section: "how to (not) brick your android image" #83

for example activating the Data Saver seems to completely brick your image: waydroid/waydroid#281

i would expect such irreversible disasters to be mentioned somewhere in the docs that i simply don't touch it and not have to find it out the hard way. 😦
i'm just not sure where to add it, as there is no such section... if not creating a new one perhaps at the Troubleshooting?